Conventional beam scales are a common fixture in health facilities, whether a doctor's office or a health club. In contrast to spring-loaded and load cell-equipped scales, which measure the effect of gravity on a mass applied to the scale, beam scales actually measure the mass itself by balancing the object of unknown mass against objects of known mass. That being said, the concept of weighing as used herein will encompass both measuring an object's mass and weight, because the force of gravity is assumed to be constant for purposes of this description.
In balancing the two masses, the object of unknown mass generally is the user, while the objects of known mass typically are metal weights, each positionable along an extension of a looped or forked beam having a pointer at a far end. Typically, the beam rests on a fulcrum at a near end, with the mass of the longer side of the beam toward the far end being offset by an adjustable counterweight on the near end. When the scale is unburdened and the metal weights are flush with the near end, the counterweight is adjusted until the beam balances the pointer at a level indicator, thereby calibrating the scale. The level indicator is located on a holding bracket attached to a frame of the scale. The holding bracket also limits the range of motion of the pointer and hence the beam itself, keeping it from shooting upward (and potentially into a user's face) when the user steps on the scale. Once properly calibrated, the scale is ready for use. When not in use and with the weights flush with the near end, a calibrated scale is resting in the “zero” position as the beam is balanced at a zero degree incline.
When a user stands on a platform on the scale, the platform exerts pressure on a series of levers within the frame which pull downward on the near end of the beam beyond the fulcrum, changing the equilibrium of the beam against the fulcrum, causing the far end of the beam to move upward and bang into the holding bracket. As the weights are slid along the extensions of the beam from the near end to the far end, the leverage the weights exert on the beam increases, causing the beam to move back downward, until the pointer levels off. If the weights are moved too far, they cause the pointer to move too far downward and beyond the balancing point. The user's weight (or mass, in this case) may be read from the positioning of the weights along the extensions of the beam when the pointer is level.
Usually, a larger weight on a lower beam extension is used to indicate increments of 50 pounds, or so, while a smaller weight on an upper beam extension is used to indicate increments of one pound or less. The lower beam extension often will have grooves indicating the position of each increment of 50 lbs., and the larger weight will lodge itself shallowly within a desired groove as the user slides the larger weight to a position of less than 50 lbs. of the user's estimated weight. By contrast, the upper beam extension often will not have grooves, but instead is smooth, with the increments printed on a face of the upper beam extension. The smaller weight likewise is smooth and includes an arrow indicating a centerline that points to one of the increments printed on the face of the beam. The user's total weight is determined by adding the incremental reading of the larger weight to that of the smaller weight.
The operation of a conventional beam scale, as outlined above, has several shortcomings. Currently, conventional beam scales do not indicate clearly that the beam has been balanced in the holding bracket. A beam is considered balanced when it has stopped moving and has leveled out in the holding bracket. When the beam is balanced, it has reached the weight of the user. Because conventional beam scale components, such as the holding bracket, are made often of fabricated metal, they are not transparent and they make loud clanking noises when users get on and off the scale. The clanking results as the components bang into each other as the shifting weight of the user causes the unbalanced beam to move rapidly upward on mounting the scale and rapidly downward on dismounting the scale. Also, the conventional level indicator typically has no indictor on the fabricated metal holding bracket. The user must estimate when the beam pointer is in line with the level indicator because the fabricated metal holding bracket obstructs the user's view of the pointer.
It would therefore be advantageous to have a beam scale with a transparent holding bracket with a level indicator that will allow the user to see the beam pointer through the holding bracket to facilitate comparison with the level indicator, and that will more quietly dampen the movement of the beam as the user mounts and dismounts the scale.
Furthermore, conventional beam scales have frames that require tools for final assembly. The use of tools complicates the construction of the scale and necessitates that a user have the required tools on hand whenever the scale is to be assembled or disassembled. The frame of the scale typically includes a base assembly, a pillar assembly, and a horn assembly. Prior to shipment of the scale from the manufacturer, the scale typically must be fully assembled, calibrated, and partially disassembled for shipment. Partial disassembly often includes separation of the base assembly from the pillar assembly using standard tools, including screwdrivers and wrenches. Likewise, when the scale is delivered, the purchaser must use tools to re-attach the pillar assembly to the base assembly and connect the levers of the weighing mechanism to re-assemble the scale. Insofar as the use of tools complicates the assembly, disassembly, and re-assembly process, manufacturing of the scale is more labor intensive.
It would therefore be desirable to design the pillar assembly and base assembly to quickly connect without the use of tools, resulting in a less labor-intensive manufacturing process and providing a potential cost savings. Moreover, materials costs may be reduced if a quick connection mechanism is designed that is less expensive than the assembly components for which tools are required. An exemplary quick connection mechanism may include a bayonet-style, pin-in-groove mechanism.
Common scale designs are based on painted, stamped-metal or fabricated metal frames assembled using spot welding. Frame assemblies typically involve a multitude of parts, many requiring painting and sub-attachment. For example, a standard horn assembly calls for a spot-welded, stamped-metal head horn assembly, having front and back head pieces spot-welded together, with a separate beam stand cap having front and back pieces screwed or spot-welded to the head pieces. The beam-stand cap houses the fulcrum and corresponding portion of the beam and may have a separate plastic cover. In addition, the holding bracket often is welded or screwed to the headpieces. Other sections of the frame similarly may have numerous-component assemblies. For instance, on the one hand, the pillar assembly may comprise several pieces welded together, while on the other hand, a separate plastic platform cover and a reinforcement plate may attach to a stamped or fabricated metal platform.
However, painting, spot welding, and the use of many components complicates and lengthens the assembly process. Simplification of the frame components, as well as their assembly, thus is desirable so as to eliminate the complication and expense associated with painting and welding the components, such as through the use of pigmented thermoformed plastic components. For example, it would be desirable to design a horn assembly combining the head horn and stand cap pieces into plastic front and back horn pieces encasing a beam support structure attached to the pillar assembly, the horn pieces bracing between themselves a plastic holding bracket. Additionally, the pillar assembly may be designed, for example, as an extruded tubular column having a quick connection mechanism at the base, while the platform may be simplified into a single piece of hard, pigmented thermoplastic or thermoset material.
Additionally, if wheels are present on a conventional scale, the wheels typically are hard plastic or metal, in part to support the heavy, fabricated metal scale, and relocation of the scale using the wheels can be a very noisy event, as, for example, the metal wheels squeak against a metal axis and the metal base. Such load and annoying noises are unwelcome, particularly in hospitals, where a scale may be moved frequently to weigh patients in different rooms, and the noises distress the hospital staff while waking sleeping patients. A beam scale having quiet wheels would be a welcome improvement over the conventional wheeled scales. For example, the wheels and ball-bearing rims commonly used on skateboards and in-line skates would be a readily available solution. Generally, the quiet wheels possibly could be made of medium-rigidity polymers.
Optionally, many conventional beam scales include separate height rods that are used to measure the height of the user. Typically, the height rod is assembled separately with extra attachments, which are exposed on the exterior of the scale, i.e., metal brackets, screws, and bolts. The height rod commonly is raised, a measuring arm is placed on the user's head at its highest point, and the measurement is taken. The measurement is read by identifying the height number on the height rod that correlates with the position of the measuring arm. This reading can be inaccurate because the measuring arm and the height numbers do not always line up, the measuring arm may move before the correlating height number is identified, or the correlating height number may be obscured when the user seeks to identify it.
Therefore, it would be advantageous to design a height rod and measuring arm that do not require hardware or separate receiving brackets for assembly, by incorporating their attachment means in the design of the pillar, and that facilitate more accurate measurement readings, by having height numbers align directly with the measuring arm and placing on the measuring arm a transparent height-measuring window having a line indicator to allow the user to see the exact height numbers.
As alluded to above, many beam scales are used in hospitals and doctor's offices for the measurement of patients' weights. Characteristic of many patients under the treatment of healthcare professionals, the user of the beam scale may have difficulty ambulating or remaining in a standing position without support. This may be particularly true with elderly patients who may require frequent weighing as part of their diagnostic monitoring. As such, the user may need to brace herself against something while being weighed. It would therefore be desirable to design a beam scale having support handle bars that may be easily attached and detached from the frame of the scale. Preferably, the user could brace herself against the support handlebars without altering the accuracy of the weight measurement.